Intravascular contrast agent T2* relaxivity in brain tissue

Patil, Vishal, Jensen, Jens H. and Johnson, Glyn (2013) Intravascular contrast agent T2* relaxivity in brain tissue. NMR in Biomedicine, 26 (4). pp. 392-399. ISSN 0952-3480

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Dynamic susceptibility-weighted contrast-enhanced (DSC) MRI perfusion measurements depend on estimating intravascular contrast agent (CA) concentrations (C) from signal intensity changes in T2*-weighted images after bolus injection. Generally, linearity is assumed between relaxation and C, but previous studies have shown that compartmentalization of CA and secondary magnetic field perturbations generate deviations from linearity. Physical phantoms using bulk blood have been used to empirically determine the relationship between relaxation rate and C in large vessels. However, the relaxivity of CA in the microvasculature is not easily measured since constructing appropriate phantoms is difficult. Instead, theoretical relaxivity models have been developed. In this study, we empirically tested a non-linear expression based on static dephasing regime (SDR) and linear approximation. Signal-time curves in white (WM) and grey matter (GM) were converted to concentration time curves (CTCs) using both expressions. Parameters for both linear and non-linear formulations were adjusted to give a best agreement between cerebral blood volumes (CBV) calculated from WM and arterial CTCs in a group of normal subjects scanned at 3T. Optimized parameters were used to calculate blood volume in WM and GM in healthy subjects scanned at 3T and in meningioma patients scanned at 1.5T. Results from this study showed that a non-linear SDR formulation gave an acceptable functional form for tissue relaxivity, giving reliable CBV estimates at different field strengths and echo times. Copyright (c) 2012 John Wiley & Sons, Ltd.

Item Type: Article
Additional Information: Patil, Vishal Jensen, Jens H Johnson, Glyn eng R01 CA093992/CA/NCI NIH HHS/ England 2012/12/12 06:00 NMR Biomed. 2013 Apr;26(4):392-9. doi: 10.1002/nbm.2876. Epub 2012 Dec 6.
Faculty \ School: Faculty of Medicine and Health Sciences > Norwich Medical School
UEA Research Groups: Faculty of Medicine and Health Sciences > Research Groups > Cancer Studies
Faculty of Medicine and Health Sciences > Research Groups > Norwich Clinical Trials Unit
Depositing User: Pure Connector
Date Deposited: 19 Aug 2015 12:08
Last Modified: 21 Oct 2022 01:09
DOI: 10.1002/nbm.2876

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